


or should I just keep chasing pavements?

by Shommey99



Series: the vacancy that sat in my heart (is a space that now you hold) [1]
Category: Life with Derek
Genre: Derek Centric, F/M, Soulmate AU, canon compliant (sort of)
Language: English
Status: Completed
Published: 2021-02-21
Updated: 2021-02-21
Packaged: 2021-03-17 13:13:54
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 14,309
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/29593311
Author URL: https://archiveofourown.org/users/Shommey99/pseuds/Shommey99
Summary: Derek wasn’t born with a soulmate mark. And that’s – mostly fine.
Relationships: Casey McDonald/Derek Venturi
Series: the vacancy that sat in my heart (is a space that now you hold) [1]
Series URL: https://archiveofourown.org/series/2174151
Comments: 22
Kudos: 70





	or should I just keep chasing pavements?

**Author's Note:**

> Heeey! Here is yet another soulmate au no one asked for! But I’m a sucker for these, so here you go!
> 
> I’ve had this idea going around in my head for so long, but I never really got to write it, because I didn’t really know where I wanted to go with it, but here it is!
> 
> The title comes from Adele’s song ‘Chasing Pavements’.
> 
> I hope you enjoy!

There’s a commotion coming from the bathroom. 

He’s finishing buttoning up his shirt when he hears a series of distinctive screeching coming from outside his room, and he rolls his eyes at his reflection in the mirror behind his door before stepping out onto the hallway.

Marti, Edwin and Lizzie are all already crowded outside the bathroom, concern etched on their faces in varying degrees. 

Derek runs a tired hand through his hair and assesses his siblings. Lizzie’s face looks freakishly white in the morning light. “What’s going on?”

“Casey’s screaming bloody murder,” Ed says, twirling his finger in a circular motion besides his head. Lizzie slugs him in the shoulder. 

The bathroom door rattles with a loud bang, making them all jump. 

“GO AWAY!” Comes Casey’s voice from inside. 

Marti shies away from the door and hides behind Derek’s legs. 

He wraps his hand around Marti’s shoulder and snaps his fingers in Lizzie’s direction. “Hey. What the hell is wrong with your sister?”

Lizzie gulps, looking at him like a deer caught in the headlights. “Her mark cleared up,” she says, absently. Marti and Edwin both gasp. 

Derek feels his breath catch in his throat, and then in a split second decision, he bends over and picks Marti up off the floor. 

“Come on, Smarts, let’s leave the princess alone with her revelations.”

Marti huffs, squirming in his arms. “But I wanna see!”

“You heard her, she wants to be alone.” He manages to restrain his sister long enough to slap the back of Edwin’s head, “You too. Let’s go.”

“But, I’ve never seen –“ Edwin starts, but Derek cuts him off with a glare. The Venturi siblings vacate the hallway and go down the stairs for school. 

Normally, he would have let his siblings harass Casey until she showed them, but this matter is a little more delicate than what Derek is comfortable with.

After all, it’s not every day that you get a Soulmate.

When they reach the living room, he deposits Marti on the floor and the girl immediately darts to the kitchen, eager to tell Nora and their dad the news, Edwin hot on her heels.

Derek sighs and rubs his eyes with the heels of his hands, already dreading what’s to come. 

If a year of living with Casey has taught Derek anything about her personality and beliefs regarding the subject of soulmates, then one thing is for sure.

_She’s going to be insufferable now._

.

.

.

On the 5th of November of 1990 at 5:50 am, Derek Venturi is born, and thus, the world becomes a cooler place.

Abby and George, young and still very much in love, excitedly wait for the nurses to finish cleaning their first born so that they can finally meet him. 

George may be unaware of the situation at first, but Abby instantly notices that something’s wrong. They’re taking too long, talking in hushed voices. 

“What is it?” she demands, her husband looking at her in surprise, then at the nurses’ backs with worry. “What’s wrong with him?”

At last one of the nurses comes to them with a bundle in her arms, and smiles at them reassuringly. “Nothing’s wrong, he’s perfectly healthy.”

George sighs in relief, but Abby somehow manages to narrow her eyes at the other woman at the same time that she holds out her arms eagerly. “Tell me.”

The nurse’s smile falters. “It’s just – We were looking, but we couldn’t find…” George feels his stomach drop. “He doesn’t have a mark.” 

Derek’s parents look at the woman in confusion, and a different, older nurse comes from behind and claps the young woman in the back. She startles and smiles again, coming over to the bed and depositing the baby in Abby’s arms. 

“Your son is perfectly fine. It’s just that in the little checkup we couldn’t find his soulmate mark. Don’t worry about it; it surely will appear in the next couple of days, it may be too faint right now. This happens sometimes,” the second nurse says, ten times more reassuring than the first. 

Abby and George look at each other in unease, but then Derek makes this soft noise from his spot in his mother’s arms, and they both look down simultaneously, just in time to catch him opening his brown eyes to peer up at them. 

All worry flees their minds. Their son is perfect. 

.

.

.

It takes five days for Abby to start panicking. 

“There’s nothing wrong with him, Abby!” George stresses, for the millionth time. 

“Then why hasn’t his mark come out?” His wife cries. 

They are standing in the nursery, where Abby had been changing Derek’s diapers, and finished another fruitless search for a mark in her son’s body.

George leans against the door frame and sighs, rubbing his eyes tiredly. He hasn’t slept in five days. A _baby’s_ soulmate mark is the least of his worries. 

“The doctors said it would, you need to be a little more patient. He’s not even a week old yet, he’s perfectly fine.”

Abby’s eyes fill with tears. She’s not normally the worrying type, but her hormones have been crazy. Yesterday, her toast fell to the floor on the jelly’s side, and she cried for _two hours_ , even after George cleaned up and made her another one. 

“What if it never happens?” she whispers, looking at her husband helplessly. “Are you seriously okay with our boy not having a Soulmate?” Her voice cracks at the end. 

The thought does twist his heart a little, but he takes his time to carefully think it over.

“Does it really matter?” George asks softly. “No one really cares about Soulmates anymore, Abby. Our marks haven’t even cleared yet. My parents’ marks never cleared!”

Abby looks away from him, and back at Derek, who was peering up at her curiously from the changing table. “My parents are Soulmates,” she says, quietly. “You don’t think we are?”

George comes over and wraps an arm around her shoulders, rubbing soothingly up and down her arms. “I’m saying it doesn’t matter. We chose each other. Derek will get to choose too. There’s nothing wrong with him. It doesn’t matter.”

Abby is silent for a moment before nodding, and she bends down and kisses Derek’s ribs.

.

.

.

When Derek is three, his mom gets really fat, and a few weeks after he turns four, his grandma takes him to the hospital to find out that his parents went and got another baby behind his back. The _nerve_! 

The baby is fat, red, and ugly, and Derek asks when they are going to give him back, only for his dad to say that they are keeping him. Derek sulks all the way home from the hospital, but when they get home, his dad says that he can get ice cream only if he gives his brother a kiss. So, happily eating his ice cream, Derek figures they can keep Edwin, just as long as he doesn’t touch any of his toys. 

But later, when he wants to show his mom how he can fling a hockey puck right through the kitchen window over the sink, she’s too busy fawning over his brother, so Derek hates him again. 

On one of the rare occasions in which Derek isn’t too busy ignoring him, he notices something about the baby. There is something black wrapped around his wrist, and when he takes a closer look, he realizes it’s imprinted on his skin. 

“Mommy, you got a faulty one,” he announces, grinning. He had learned that word recently, when one of his Fruit Loops had come in a funny shape. ‘It’s a faulty one’ his dad had said. 

His mom chuckles and approaches him where he’s standing on his tiptoes peering down Edwin’s crib. 

“What do you mean, buddy?”

Derek points a finger towards his brother’s wrist. “He has a black spot there.”

“Oh, that is not a defect, Der.” His mom rolls up her sleeve. “It’s like this in my arm.”

She shows him a black spot similar to Edwin’s that she has on her forearm. It looks really cool, like a lightning bolt.

“They are called soulmate marks,” his mom explains. “At first they are a blurry smudge like Edwin’s, but they become more defined with age, until one day they turn into the name of your soulmate.”

Derek pulls away from the crib, eying his mother’s mark curiously. “What’s a soulmate?”

“It’s the person you’re meant to be closest to in the world. It’s the person that best matches you out of everyone else.”

“Oh,” he says, and then frowns, looking down at his arms. “I don’t have one.”

He notices his mom’s smile falters for a second, before she kneels down on the floor and hugs him abruptly, squeezing tight. 

“That’s because you’re special, baby,” she says, her voice muffled by his shirt. “Some people don’t have marks.”

“They don’t?”

His mom pulls away from him and smoothes down his hair. “It’s very few people. That’s why you’re so special.”

“But is it – isn’t it bad?” Derek asks. If everyone has a mark that makes them match with someone for life, and he doesn’t have one… He pouts. “I don’t match with anyone. I’m left out.”

His mom’s voice breaks, and Derek’s frown deepens. “No, honey, it’s not bad at all. It doesn’t matter. Most people don’t match.”

He looks at her skeptically. “They don’t?”

“No,” she says. “Your dad and I love each other very much and we don’t know if we match. I know a lot of people that are married that don’t have matching marks.”

“Oh,” Derek says, his mood already better. “So, it doesn’t matter?”

She sends him a wobbly smile. “No, baby.”

Derek thinks it over for a few seconds, and then he hears the Teenage Mutant Ninja Turtles theme song coming from the TV downstairs and he bolts out of the room. 

“Cool!” he shouts over his shoulder, slamming the door on his way out. The baby starts crying and Abby sighs.

.

.

.

After that, Derek starts noticing that everyone has marks. Most adults like to hide them with clothing, but kids don’t, and he finds that he’s fascinated by them.

His next-door neighbor, Emily, has hers on her knee, and it constantly makes it look like she fell and scratched it – which is really cool. His friend Colin from Hockey has his on his elbow. And he even saw a man on the supermarket with a mark on his forehead!

Edwin’s is on his wrist and looks like a bracelet. His dad’s on his calf and looks like a splash of black paint. Marti’s is on her shoulder and looks like a heart. And his mom’s is on her arm and looks like a lightning bolt.

Derek likes to ask people about their marks, and he likes to tell them that he doesn’t have one in turn. It’s funny when they make surprised faces, but not so much when their faces fall with pity, so he stops telling them about it.

He’s only sad that he doesn’t have a soulmate mark sometimes, but that makes him different, and he likes to stand out, so he doesn’t mind. He’s special.

He’s even seen some people with their marks cleared, but that’s even rarer to see in public, because marks are private and intimate, according to his mom. He learns that people can have marks in different parts of their bodies and still match, but some people believe the bond is even stronger when the marks are on the same spot.

His grandparents are soulmates, and they have matching marks on their palms, each other’s names imprinted on their skin. Derek wonders when his parent’s marks will clear. 

He figures it’s cool if it happens, but lightning bolts are cooler than names. 

.

.

.

Derek is ten and he’s sitting on the floor playing with his toddler sister just by the dinner table, where his mom is working on her laptop, furiously tapping away as she smokes cigarette after cigarette. Derek turns to her to ask her when they’re going to eat dinner, when the mark in her arm catches his eye.

It’s different. It’s not just a lightning-shaped spot anymore, there’s letters. His heart jumps excitedly and he turns his head to the side as far as he can so that he can read it right side up and yup – 

That is _not_ his father’s name. 

About two days later he hears them arguing in the kitchen. 

“I’m so sorry, George.” His mom is sobbing, and Derek has never seen his parents cry. Adults are not supposed to cry. He hates it he _hates it_. 

His father’s voice is the most broken he’s ever heard it, even more than when Grandma died. “We have _three kids_ , Abby.”

“You know it’s not working. It hasn’t been working for a while.”

There’s a silence in which his father grips the kitchen island, and Derek presses himself further against the sliding doors. 

“Tell me you wouldn’t be trying to make it work if your mark hadn’t cleared.”

Derek feels his eyes grow wide and Abby stays silent. 

“I can’t believe you,” his dad says. “You told our son that all that shit didn’t matter and now you want to _leave_?”

And he doesn’t want to hear anymore. He moves away from the kitchen doors and turns around to see Edwin and Marti standing at the bottom of the stairs. His brother looks like he’s about to cry – _no more crying, please stop the tears_ – his hand completely engulfing their little sister’s, who looks confused. 

Derek squares his shoulders and marches up to them, picking up Marti with difficulty and grabbing Edwin’s hand, tugging them both up the stairs and into his room. 

His parents don’t last long after that, and Derek doesn’t feel fascinated with Soulmate marks anymore. 

His father’s is on his calf, Edwin’s is on his wrist, Marti’s in on her shoulder, and his mother’s was on her arm. 

He doesn’t ask anyone about theirs ever again.

.

.

.

Ultimately, Derek decides that if there is one thing soulmate marks are, is _stupid_. 

The more he grows up, the more he realizes that most people live well into their adulthood without their marks clearing. What is the point of that? Saving yourself for someone who you might not even like or meet? Waiting for something that may never happen? 

And then again, if it happens – being tied to someone for the rest of your life? 

Soulmate marks clearing are the first leading cause of divorce.

He can’t think of something stupider than going back on a decision because the universe says ‘oh, wait, you’re more compatible with this other dude, time to go back on all your promises and plans’.

He honestly respects the hell out of people who don’t care for soulmates, because they. Are. Stupid.

Derek used to think he was unfortunate for not having a soulmate, but now he realizes – he’s lucky. He’s absolutely free. Whereas people have something tying them to someone against their will forever, he’s not – _nor will he ever be_ – tied to anyone. 

It’s a pretty good deal if you ask him.

Derek Venturi is a lucky guy. He’s a hockey god, he’s got girls lining up to go out with him – who only find him hotter when they find out he doesn’t have a mark – he’s got great friends, he’s on his way to being the most popular guy in school. 

He wasn’t born with a soulmate mark – and that’s fine. He doesn’t want one. 

.

.

.

He is not as ashamed of ‘Operation Disengagement’ as Casey is, and after the whole restaurant proposal debacle, he only fights his dad about his upcoming marriage once, a week before the wedding.

“Just tell me what is so _special_ about Nora that you want to _marry_ her, and bring her _and_ her daughters into _my_ house – “ _Into my mother’s house._ Derek doesn’t say it, but he can tell by the look on his father’s face that he understands. “And ‘I love her’– “ He emphasizes with quotations marks, because how long have they known each other again? “ – Isn’t going to cut it.”

George stays silent for a second, breathing heavily while staring at the floor, his hands perched on his hips, and it suddenly occurs to Derek that he hasn’t seen him in short pants or his underwear in a while.

His father meets his eyes and Derek recoils. “Is she – are you _soulmates_?” he practically spits the word out, vexation reflecting in every bit of his body language.

George only exhales slowly out of his nose in response, his shoulders slumping.

Derek feels something akin to an anvil falling from his chest to his belly. Silence stretches in his room, and he just nods. “I see.”

His dad takes a step towards him. “Derek, just let me explain it to you.”

“I get it,” he cuts him off. He doesn’t need his dad to explain to him something that he has already explained a thousand times, just tweaking some stuff to fit into his narrative better. He has listened to his mom do the exact same thing and it wasn’t worth it. He grabs a magazine from his desk and slumps in his bed, opening the issue on a random page and staring hard at it. 

“Derek…”

“It’s fine.” _It’s not it’s not._ He flips a page. “Close the door on your way out.”

And so, his father remarries.

.

.

.

Derek cannot get used to the new sitting arrangement. 

Edwin is way too close for comfort, and they knock elbows almost every time either of them moves. There’s no room to sprawl his feet under the table without kicking Casey’s legs, and they’ve already started like, three food fights _this week_ about it. He’s not comfortable with Nora’s watchful glare whenever he burps – _this is a men house, for fucks sakes!_ – and Lizzie, well. Lizzie hasn’t really done anything to annoy him. _Yet_.

They’ve been living together for what? Three weeks? And it’s already proven to be every bit as painful and annoying as Derek had expected it to be. In between fighting to keep their righteous place and status in their own house and trying to keep a certain _princess_ from changing everything that’s good about their home, everything is exhausting.

But, his dad is happy – happier than he’s ever seen him so _whatever_. He’ll manage. He always does. 

Derek’s almost finished inhaling Nora’s lasagna when Edwin pipes up from beside him.

“Hey, Lizzie, you have some dirt on your neck.”

Lizzie’s hand flies to her neck and she rubs, before a look of realization dawns on her face. She turns bright red. “Oh, it’s not dirt. It’s my mark.”

Derek instantly snaps to attention, his eyes going straight to Lizzie’s neck, and he mentally kicks himself for the kneejerk reaction. 

“Your Soulmate mark is on your neck?” Ed exclaims, surprised.

“Yeah,” Lizzie says, sheepish. “I can’t really cover it, it’s kind of embarrassing.”

Casey puts a hand on her sister’s shoulder and smiles at her sympathetically. “It’s nothing to be embarrassed of, Liz.” The girl smiles a little, but she still looks awkward.

“I agree,” Edwin says. “I think it looks badass.”

“Edwin,” Nora says sternly, berating him for his language. Derek resists the urge to roll his eyes. What the hell is wrong with the word ‘badass’, anyway?

“It _does_ look badass,” Derek says. It kind of looks like a tattoo of a star.

“Derek,” George chides this time, and Derek does roll his eyes.

Lizzie grins more genuinely. “Thanks.” 

Derek watches as Casey frowns a little, obviously put out that she was not the one to cheer up her sister. She’s so easy to read, it’s kind of pathetic. 

Edwin extends his left arm towards the table and dread pools in Derek’s stomach quickly. He already knows where this is going. His brother moves aside his watch to reveal his Soulmate mark.

“Check out mine.”

Lizzie leans over the table, squinting. “It looks kind of like a bracelet,” she says. 

“Well, you know Ed’s always had a feminine side,” Derek snickers.

Casey glares at him from across the table, “I think it’s cute, Edwin.” 

“I’m not cute,” Edwin scrunches up his nose.

Casey ignores him. “Mine is on my ribs.”

Marti jumps. “Mine is on my shoulder! It looks like a heart, see?”

The table falls silent after that, and Derek is trying hard to concentrate on finishing his plate of food, but he can feel everyone’s gaze on him. Casey kicks him under the table, and he snaps his glare up at her. She crosses her arms over her chest with an expectant expression. 

“What about you?”

He holds her blue eyes steadily, already feeling the now familiar adrenaline rush that always kicks in whenever they stare at each other challengingly. “What about me?”

“Your mark,” she prods, not backing down.

Derek shrugs. “Not much to show and tell there.”

She raises a skeptic eyebrow. “Meaning?”

“Derek doesn’t have a Soulmate mark,” Edwin announces, admiringly. “He’s meant to be a lone wolf forever.” 

Marti howls in imitation of a wolf and Derek smirks at Casey’s horrified expression, a rush of immense satisfaction going through him. It’s been almost a month – will he ever get tired of that look on her face? He doubts it. 

“What do you mean you don’t have one?” she asks, in her shrill, pretentious tone. “That’s impossible.”

George clears his throat, and everyone turns to look at him. “Actually, it’s not. At least one in ten thousand people are born without any marks. Derek is one of them.”

Casey frowns, and Derek can see the gears turning in that head of hers. “But maybe it could appear later on in their lives. Everyone matches with someone.”

“Apparently it’s happened for some people, but most just never get one,” his father says, shrugging. It’s become a common theme in their lives now. Derek knows that during the first years of his life his mom held onto hope that it would happen, but now they’ve all accepted it won’t. 

Like he’s already stated, Derek is fine with it.

He feels the smug smile practically fall from his face the moment he notices the particular shine in Casey’s eyes. 

_Tears._

“That’s so sad,” she says, voice strained. “It’s nature. Why wouldn’t they have soulmates?” And she looks at him, wide eyed and compassionate, and Derek feels his gut twist with silent, irrational rage.

He clears his throat, bracing his hands against the edge of the table and not breaking eye contact with her for a second. “You know what’s _real_ sad?” he drawls, and revels in the way her expression goes from pity, to confusion, to wariness. “Falling down the stairs in school and injuring like, three people, like some kind of human snowball.”

She gasps, and the entire table turns to her.

“What? Casey, what happened?” Nora asks, concern laced in her voice. 

“Cory’s butt will never be the same,” he announces, and Edwin and Marti snort in laughter. 

Casey’s eyes fill to the brim with renewed tears, and she hates him, he can tell. He feels just a little pang in his chest.

“That was your fault,” she accuses, enraged.

Derek breaks eye contact and turns to the table at large. “They call her Klutzilla.”

Edwin spits out his water in laughter. “ _Klutzilla_?”

“ _You_ call me that!” Casey exclaims, gripping the tablecloth. 

“Everyone calls you that.”

“Because you told them to!” 

She’s crying and it’s satisfying, but it’s also not, and that feeling of winning and losing at the same time is going to confuse him for a while. 

His father is chastising him, Nora and Lizzie are concerned, Marti and Edwin think it’s hilarious, and Casey scrapes her chair loudly against the floor as she gets up and leaves the table, stomping up the stairs to her room. 

“Derek, honestly,” his father says, shaking his head in disapproval. 

Derek has a smirk on his face, even as he stabs at his last piece of lasagna violently. The table falls silent, and well, he’d known it was only a matter of time until Lizzie annoyed him. 

.

.

.

Derek loves Sam. 

Seriously, he does. He was the first person he made friends with after repeating first grade, and they’ve stuck together ever since. 

Sam loves hockey almost as much as Derek does, and they can play video games for hours on end without getting bored, and he’s literally the chillest person Derek’s ever met, even more than _he_ is – and honestly, this is what long-lasting friendships are made of.

He loves Sam.

But if he keeps looking at Casey like _that_ , Derek might have to _murder_ him.

He’s never been a violent person, but there’s just something about his best friend drooling over his step-sister at the dinner table while Derek tries to _eat_ , that just makes him want to throw something. _Hard_. 

At Sam’s head, preferably. 

Does Derek have to invent a male code for Sam to know that Casey’s off limits? She practically comes with the ‘do not touch’ label all over her. And Derek gets it, really he _does_. He has eyes. He’d never, in a million years, admit it but yeah – he _gets it_.

But there are a million girls in school that Sam could go for if all he’s looking for is ‘blue-eyed and hot’. Uncomplicated girls. Cool girls. Girls that are not Derek’s.

Not Derek’s step-sister, _obviously_. 

But that’s not even the point; the point is that Sam is too mellow for Casey.

A guy like Sam can’t handle a girl like Casey, _hell_ , Derek’s not even sure if _he_ could handle – 

But that’s not the point either. 

The point is that Casey’s already taken over _so_ much of his life, like hell he’s going to let her take over his best friend too.

That’s the worst part of this whole Sam-and-Casey-liking-each-other crap. 

Derek is possessive, he can admit that. If something’s his, then it’s _his_ , dammit. And Sam is _his_ best friend. This is not some brotherly concern towards Casey because, yeah, no matter which way you slice it, he just can’t fit that into his argument – but this is _definitely_ about his relationship with Sam.

It doesn’t matter that in this scenario _Sam_ is the one that Derek wants to murder, he totally is just looking out for his friend, thank you very much.

It’s not his fault that his friend is being an idiot. 

And speaking of idiots, what the hell does Casey even want with Sam? 

Isn’t she like, obsessed with true love and soulmates and all that shit? This is the same girl that tries to convince Derek to take off his shirt to prove that he doesn’t have a mark.

Okay, maybe she didn’t explicitly ask him to take off his shirt, but that’s totally what she meant.

So why does she even want to waste her time with Sam instead of waiting for Mr. Right? 

Because there’s just _no way_ that Sam and Casey could be Soulmates, right? 

Anyway, who cares about that shit? Not Derek! 

It’s fine. It’s not like they would work out anyways. It’s just a fact of life, Derek knows about this stuff.

And besides, what Derek wants –

Wait.

That’s not the phrase that goes with this reasoning. 

.

.

.

The thing is, that even if you spend your entire life convinced of something, there are still moments that make you doubt. 

Not change your mind, because Derek doesn’t dwell on things long enough for them to do long-term damage to his belief systems, but even _he_ gets moments when he just… doubts.

The week is ending something like this –

He’s the last one coming down the stairs for breakfast on Thursday morning, as usual. Edwin and Lizzie are already bickering over cereal, and Marti’s eating hers on the floor. And Casey looks, well, she looks worse than most days, and that’s saying something. 

“Is it morning of the living dead? I thought Fridays were zombie day,” he says as he sits facing her on the kitchen island. 

Casey groans into her cereal. “I didn’t sleep well last night. I had a lot of nightmares.”

Lizzie looks at her sister sympathetically. “What did you dream?”

Casey shudders and glares at him. “Derek was chasing me around with a tarantula.”

Derek smirks, satisfied by a job well done, even if it was her subconscious doing all the work for him. He’s just _that_ good, apparently. “Do I star in your dreams often, Space Case?”

And the thing about living together for a year is that Casey doesn’t really take any of his shit anymore. Don’t get him wrong, she still rises to every challenge, and Derek knows her well enough to hit just the right spot to make her scream, but he doesn’t do it if he doesn’t have to.

Well, not if he’s feeling generous anyway. 

So instead of blushing, and sputtering, and yelling, Casey just smirks right back at him, positively brightening his morning. 

“Oh, yeah,” she says. “Monday night I dreamt that your parents sent you to military school. It was awesome.”

“Oh, wouldn’t that be a dream come true for you.”

“I was so sad when I woke up.”

They smile at each other more genuinely than he’d like to admit, and the rest of the day is mostly normal. He avoids Kendra, eats lunch with Sam and Ralph, and goes to hockey practice. And he must have had it rougher than he’d realized, because his body _hurts_.

He’s showering after and his ribs feel like they are on fire – did he take a puck to his torso? He can’t remember. He’s restless in his sheets all night, tossing and turning until he finally gets to fall asleep. 

When he comes down for breakfast Friday morning, overtired and irritated, everything is the same as the previous day except that Casey is nowhere to be seen. 

“Where’s Space Case?” he mumbles, snatching the cereal box out of Edwin’s hand. 

Nora, who was previously beating around the kitchen looking for something, pauses, looking up at the clock on the wall.

“Uh, she hasn’t come down yet? Maybe her alarm clock didn’t go off? Derek, would you please go wake her up? She’s going to be late and she hates being late.”

Derek grumbles, but pushes himself away from the table when Nora sends him a withering look. He slowly climbs his way back up the stairs and makes a beeline for her bedroom door, pounding on it obnoxiously. 

“Ca- _sey_!” Hey, if she gets to mangle his name, why can’t he? “Get up, you have a whole day of keener-ing to do!”

There’s no answer from inside. No sound of a body rolling off and falling from a bed, or a mad scramble to get dressed.

He frowns, and slowly turns her doorknob, “Case?”

The door opens and he almost jumps out of his skin when he sees her standing there, still in her pajamas, her arms hugging her waist. 

“Uh, what’s wrong with you?”

She’s staring at his chest, a soft frown on her face. “I don’t feel well,” she says, in a small voice.

He takes a step closer to her and she immediately jumps backwards, eyes widening. Derek’s eyebrows rise.

“O-okay,” he says, confused by her behavior. “Well, are you not coming to school?”

Her eyes snap up to his, and Derek notices she’s flushed. “I never miss school.”

“Well, then get moving, or I’m leaving without you.”

Casey stares at him expectantly for a few seconds. 

“What?”

“Um, I need to go shower.”

She normally would have just pushed past him. He reaches a hand to her forehead. 

“Are you – “

She cranes her neck backwards, avoiding contact, cheeks reddening further. Derek frowns. 

“Shower!” she exclaims suddenly. “I’m gonna – yeah.”

She pushes past him and hits her shoulder against the doorframe in her haste – and he suspects, for the sake of not touching him – and scurries towards the bathroom, leaving Derek standing in her doorway.

It takes a few seconds but he composes himself and shrugs, going into his room to change.

And then, there’s a commotion, he finds his siblings outside the bathroom door, and Casey gets a Soulmate.

.

.

.

Sometimes, he’s pretty sure he knows Casey backwards and forwards.

It’s not even like he did it on purpose, but somehow, in between the pranks and the smack-downs, and the begrudgingly helping each other out of holes they dug themselves, he _knows_ her.

Tragically, she knows him too, but that’s not the point.

The point is, that even when he thinks he knows exactly what she’ll do next, how she’ll react, there’s still moments when she’s completely unpredictable.

Like now, because –

Casey getting a Soulmate? 

He was half expecting her to start hanging pamphlets at school, announce it through the speakers at the mall, or broadcast it in the local news. 

_‘Sir Dorksalot, my name is Casey McDonald, and we’re Soulmates, I’ll be waiting for you to come and sweep me off my feet so we can ride off into the sunset together, preferably at short notice.’_

This is _huge_.

Shouldn’t she be happy that finally she has an opportunity to meet her actual Prince Charming? 

Apparently not, because she closes herself in her room for a week. 

It’s not that he cares, because _he doesn’t_ , let’s be clear on that. 

But Casey avoiding everyone is… just a little concerning.

Lizzie practically camps outside her bedroom. Emily comes over every day to try and talk her out of her self-confinement. Marti sings to her through the gap between the door and the floor. Edwin is staying as far away from her as Derek is, because even if he’s the sensitive one, he doesn’t know how or wants to handle _that_ either.

In the moments she has to sneak out to go to the bathroom or to grab something from the kitchen, everyone just stays frozen in place looking at her as if she’s a bomb about to go off at any moment. But she just does her business and avoids eye contact.

Derek overhears Nora telling George that she’s worried, ‘because you know how Casey is with this things, Georgie’ and she’s ‘too young to have a Soulmate’, and she’s ‘going to stop living her teens and dating’. 

And _shit_ , Casey has a _Soulmate_. 

Why does it really feel like everything is over? It’s not even happening to him.

_It’ll never happen for him._

Derek only tries to approach her once, when they bump into each other on her way to the bathroom, and maybe he’s crazy, but it kind of feels like she’s avoiding him more hardcore than everyone else.

And he kind of gets it, because he never takes anything seriously – her words, not his, but yeah, okay – and this is like, the most serious thing to ever happen to her.

But she can always trust him to lighten up the mood. “I see getting a Soulmate doesn’t erase the klutziness.”

And when she just tenses and makes a mad dash for the bathroom, he just sighs.

It all culminates in a family emergency meeting that Casey herself invokes, to talk about _herself_ , and isn’t that just the most Casey thing ever?

She finally meets everyone’s concern – she doesn’t glance at him once – and tells them all that “As you all are well aware, my Soulmate mark cleared.” – Why does she talk as if they were in a conference? – “I want to state that I felt everyone’s support throughout this life-altering event” – She didn’t let anyone talk to her – “But I hope you can all respect the fact that the identity of my Soulmate shall remain private, and I will not be persuaded otherwise.” – Now _that_ gets everyone’s attention, because hasn’t she realized that her family is full of snoops? 

She cries almost the entire time she’s talking to the fam, much like Nora, who’s quietly wiping her tears on a napkin with one hand as the other holds Casey’s, and Derek chances a glance towards Lizzie to find that she looks extremely uncomfortable with the display – her lips are turned down and she’s pressed back against the cushions as if the couch could swallow her – and he always knew that Liz was the only semi-sane person in the McDonald clan. 

Marti looks a little confused with all the drama, and Edwin looks like he’s trying his best to hold his laughter in, and this _is_ hilarious, Derek doesn’t know why he’s not laughing. 

Maybe it’s because Casey won’t look at him so that he can send her one of his looks that will have her screaming ‘De-rek! You insensitive jerk!’

And why isn’t she looking at him? Is it because she knows that this’ll never happen for him? Does she still pity him? He can’t take pity from anyone, especially from _Casey_.

She’s _not_ better than him.

It takes him a few hours, but Casey and Derek and boundaries? Yeah, never heard of those three things in the same sentence.

Standing outside her doorway while he deliberates, he thinks about how much his relationship with Casey has changed over the course of a year.

Don’t get him wrong, he still finds her to be annoying and judgmental as hell – the most nagging, neurotic, goody-two-shoes person he’s ever met.

And, the idea of her _(of all people)_ getting a Soulmate _(of all things)_ , still makes him extremely uncomfortable, in more ways than he’s willing to analyze. 

But – 

She’s also the first and only person in his list of ‘People who would actually fight a gigantic football player for me’, so he knocks on the door and waits for her ‘Come in’.

Casey looks up from her place on the bed, a little apprehensive frown on her face, but she’s not avoiding his gaze.

“What?”

Derek strides towards her desk chair and unceremoniously slumps down on it, putting his feet up on her bed. 

“So, are you sticking with that whole ‘my Soulmate’s identity shall remain private’ thing? I kind of thought it would be of public knowledge by now, on a national scale.”

Casey rolls her eyes and pushes his feet off her bed. 

“What made you think that?”

He rises his feet again, this time closer to her thigh. “Um, I don’t know, maybe your whole personality?”

She starts untying his shoelaces. “Well, maybe you don’t know me all that well.”

He lets her take off his shoes as he sends her an unimpressed look. “So, who is it?”

Casey looks away from him, back towards the book she had been reading. “Derek, I said I wouldn’t be persuaded. Nothing you say will make me tell you.”

Derek leans forwards and snatches the book out of her hands. “How bad can it be?” He makes a dramatic pause, before gasping. “Is it Tinker?”

“De-rek! Don’t be mean. And no, it’s not.”

He leans back against the backrest of the chair with a smirk, “Oh, is it worse? Like, Mussolini worse?”

“Mussolini is _dead_ , Derek,” she deadpans.

He shrugs. “Well, you’re not very lucky in the men department.”

That gets her. She laughs despite herself. “God, shut up.”

They stay silent for a minute when an idea comes to him, something he’s been wondering for a while. 

He clears his throat, and tries to keep his tone light. “Well, is there a possibility of it being… a girl?”

There is a tense silence in which Casey looks at him wide eyed.

He rushes to add. “Because that would be okay.”

They lock eyes for another minute, and he doesn’t know when she decides she trusts him, but she swallows hard and nods.

“Oh,” Derek says.

Casey turns a few shades pinker. “Just to clarify, I’m not saying it _is_ a girl… but it wouldn’t be, you know, all that far-fetched... for you to think that.” She coughs.

Derek isn’t surprised by the revelation, per se – Casey’s _not_ subtle about her crushes. Just last week, Sally had winked at her and she had spilled all of her tea on her lap. 

What’s surprising is that she so willingly shared it with him.

Yeah, their relationship has definitely changed.

He tries to disperse the awkwardness by nudging her leg with his foot playfully and she snorts out a laugh, grateful by his silent acceptance. 

“Come on, you can trust me,” he says, with no sincerity in his tone whatsoever. “What name is it?”

Casey sobers up and turns to look at him. He feels a strange sort of uneasiness as her _(so very blue)_ eyes search his, seriously. Derek doesn’t think she’s ever looked at him so intensely, but he can’t bring himself to look away.

At last, she speaks. “Do you really not have one?” It comes out almost as a whisper.

The question catches him off guard. He still doesn’t know why she’s so obsessed with his mark – or lack thereof, but for the first time since she first asked, instead of annoying him the question makes his stomach churn. 

“No, I don’t,” he says, sincerely. 

Casey’s lips turn down, and she looks away from him. He releases a breath he didn’t know he had been holding. 

“I don’t know,” she sighs, “Maybe you’re right. Maybe they are bullshit.”

Derek eyes her suspiciously for a second, “Who are you and what have you done with Casey McDonald?”

She snorts again.

“No, seriously,” Derek says, “Aren’t you supposed to be a romantic at heart? Aren’t soulmate marks like, the ultimate sign of true love or whatever bullshit?”

Casey shakes her head, frustrated. “I don’t know. I’ve been thinking about it all week and I found some flaws in the system.”

Derek raises an eyebrow, amused. “‘The _system_ ’? I thought it was ‘nature’?”

She narrows her eyes at him, “It’s just. Take polyamory people for example. It doesn’t make so much sense that all of them would only have one soulmate. Some people don’t even get romantic feelings ever. It doesn’t make sense entirely.”

“There are a lot of documented cases of people with more than one soulmate,” Derek says, “Also, platonic soulmates. And people that killed their soulmate, people that never even met them, and people whose marks never cleared.” 

Casey just stares at him, dumbfounded.

“It’s not a system, Space Case. It just _is_ ,” Derek explains, “Although, the Church has tried to make registration of soulmates mandatory by law for centuries, you know, so everyone can marry who ‘God mandated’,” he adds, almost as an afterthought. “They even do it in some countries.”

“How do you even know all this stuff?” Casey asks, wide eyed. 

Derek shrugs. “My mom’s a scientist. She spent a shit ton of time researching soulmates when I was a kid. You know, because I don’t have one.”

Casey frowns, “So, people who are not marked just… don’t have soulmates?” Her voice rises weirdly at the end of the sentence. 

He groans. “God, you’re not gonna cry about this, are you? I already told you, I don’t give a shit.”

“It’s just been a really emotional day,” she sniffs, offended.

Derek rolls his eyes. “You just got a soulmate, Space Case. You should go look for them and live your happily ever after.” He gets up from her bed. “Stop thinking so hard about it.”

And with that, he leaves her room.

She breaks up with Max shortly after that.

.

.

.

The thing about his relationship with Casey is… well. There isn’t really a way to describe it. 

He’d tried to convince himself that it was one of those ‘ignore it and it’ll go away’ sort of things, except he can’t ignore it and it won’t go away.

So, instead it’s an ‘ignore it and live with it’ sort of thing.

And it was going fairly well before her mark cleared up. He could totally handle some light touches or lingering gazes, the unnecessary wrestling, and the occasional shameful, _shameful_ showers, but… 

It somehow gets weirder. 

Because Casey gets weirder, and honestly, who would have thought that that was even possible? 

It’s like one moment she’s normal – or at least, Casey-normal, and the next – 

They are playing a board game with the fam that Lizzie and Casey used to play in their condo in Toronto, the usual competitiveness sparkling in the air.

Derek wins, nothing unusual about that, and when he turns to her to gloat, something shifts.

“Face it, Case, you just got owned at your own game. I _own_ you.”

The red fury leaves her face and she turns a little white, her face falling. And then, out of nowhere – 

“Fuck you, Derek.”

His eyebrows almost reach his hairline, Lizzie and Edwin both widen their eyes and Marti kind of giggles at the foul language. 

After the initial shock wears off, Nora starts scolding and Casey pushes away from the table, stomping her way upstairs. 

George, for some reason, thinks Derek’s due some berating too, and Derek looks at his dad incredulously. 

“Are you seriously going to blame _me_ for this? It’s not my fault that someone is _insane_!” He shouts out the last word, and a door can be heard slamming in the distance. 

– Other times, she’s quieter, like when they’ve been arguing on the line at the supermarket and the cashier mistakes them for a couple.

Derek denies it in good humor, he makes jokes about the man needing glasses, and at Casey’s expense, waits for her to retaliate with a few quips of her own, but she keeps uncharacteristically silent. 

They go back home with the groceries and the entire car ride she’s left staring at the distance with a frown on her face, looking mildly disturbed. 

Another day, reaching the end of their junior year of high school, Emily invites them over to her pool. 

(For Casey’s 17 birthday, Emily gifted her a bikini. It was hot pink and tiny, and Derek was not **looking** , but he was _looking_.

And the look on Casey’s face when she had seen it had gone from delighted to apprehensive, and then she declared that she didn’t wear bikinis – and that’s a lie, because he’d seen her with her navy blue bikini before, the image was seared into his brain.

And then it hits him that what she meant is that she doesn’t wear bikinis _anymore_. Not since her mark cleared.

And so, she sadly places it back on the gift bag, intent on going to the shop and change it. And only Casey could do humanity such a disservice by not trying it on at least.)

Anyway, so they are at the pool, Sam and Ralph already splashing around. Casey’s in her sensible one-piece suit – which she somehow manages to look hot in – and Emily is inside getting them drinks.

Derek takes off his shirt over his head and briefly looks up to find Casey’s eyes raking over him. He revels in the weird ego boost he feels every time he catches her staring, but then he realizes that this is no normal ‘Casey trying to be subtle as she stares’ routine, no, her eyes seem to be searching for something, rapidly moving from his abdomen, to his chest, to his back.

“Are you actually looking for it?” Derek exclaims, incredulous. Their friends stop what they’re doing and look over at them. “I already told you a million times I don’t have a fucking mark!”

Casey blushes furiously and she stutters. “I-I wasn’t looking for a mark!”

Derek scoffs, setting his hands on his hips. “Oh, were you just checking me out, then?”

Casey pauses, opens and closes her mouth like a fish, obviously debating which option is less embarrassing. “It’s just weird that you don’t have one!”

He buries his face in his hands. “Oh my _god_.”

“It could be a medical condition!” Casey continues, frantically. “Maybe it’s a tumor? You could be dying!”

He can hear Sam and Ralph laughing in the pool, and Emily’s standing in the backdoor of the house with an exasperated yet fond look on her face.

“I’m not dying!” he yells. And then he mutters, quietly. “They already ran all the tests.”

After some more rambling, he ends up picking her up and throwing her in the pool, if anything to shut her up. If he gets to touch her thighs in the process, well. 

“You guys are so weird,” Emily says, suddenly standing beside him 

And yeah, he knows she’s right. 

.

.

.

The first time it _really_ bothers him – no, really, this is the first time – comes with Sally. 

Her mark is on her ankle, circling around it delicately, making it look like a sexy tattoo. It’s not cleared and Sally doesn’t even mention a concern for it. And Derek is not concerned.

But he’s well aware of the fact that his smart, beautiful, totally-wasting-her-time-with-him girlfriend has a Soulmate that’s not him. 

It hasn’t occurred to him until now that maybe he’s been running away from love a little bit.

And he was right for it, because Sally is fucking _leaving_.

She’s leaving, and Derek’s set on going with her, and he and Casey get into their weirdest fight yet.

“You can’t do this, Derek.”

“It was your idea in the first place!” he shouts at her. They’d already done the whole opposite game shit and she had lost, did she really have to keep pressing the subject?

“I was kidding!” she shouts back, hands on her hips and straightened hair almost standing up. 

“Well, you were right,” Derek informs her, clapping sarcastically. “Congrats on finally giving me a good idea.”

Casey shakes her head. “No, I wasn’t.” She takes a step towards him, way too close for comfort, and her blue eyes lock with his pleadingly. “How are you planning on doing this, Derek? You throw away your future here, follow Sally to Vancouver and one day her mark clears up and –“

And she just has to fucking _go there_.

Derek snaps. “God, are you fucking kidding me?” Casey’s eyes widen and she reels away from him. “What the fuck do you care? Why don’t you worry about your own fucking soulmate instead of butting into other people’s lives?” 

Casey’s mouth snaps shut, and her eyes fill with tears. Derek feels the anger drain out of him quickly, and he runs a hand through his hair, frustrated. 

“Fine,” she says, voice strained. She turns around and leaves his room, closing the door softly behind her. 

The worst part is, he knows she’s right. He’d seen it happen to his parents after years of marriage, and he doesn't stand a single chance. 

Later, Sally rings on their doorbell, and he has to face the pain of breaking up. 

Sally plays softly with the hair at the nape of his neck, and smiles at him softly. “I’ll miss you so much.”

He closes his eyes and takes a shuddering breath, “I already miss you.”

When he opens his eyes, Sally is giving him _that_ look, the one that always makes him wonder how much she actually _sees_ of him, how much more she knows than just what he lets her in on. 

“You’ll be alright here.” There’s a small smirk playing on her lips, and it takes him back to the day she had invited Casey along with them to a lame expo in the museum, and he had groaned and complained the whole way there, while the two girls talked excitedly.

The three of them walked through the stands, losing each other in between displays.

In a moment of quiet, while he was disinterestedly reading the description of one of the art pieces, he felt someone stand beside him.

The back of a hand brushed his and he closed his eyes, suddenly exhausted, and he let himself pretend that it was Sally’s. But he knew it was not. Still, he wouldn’t look to the side to prove his theory.

Or move away, for that matter.

He doesn’t really understand the way his brain works, but sometimes it’s not all that simple. 

When Sally and Casey are both distracted, he leaves the expo and goes home.

“I’m not so sure of that,” he tells Sally now.

She reaches over and hugs him tightly. “I am.”

.

.

.

His last year of high school goes by without much incident. 

He binge-dates in an effort to get over Sally, and enjoys his friends in their last year.

He almost doesn’t make it to graduation, but he manages to pull through in the end, like he always does. With Casey’s help, of course, but that’s not the point. 

Casey dates ( _gag_ ) Truman, and then they break up. 

He dates Emily, and then they break up.

His dad and Nora make a McDonald-Venturi spawn, and he pretends he doesn’t see Casey’s frozen horror before she congratulates them. 

And hey, she does the same for him – their practiced delight is a team effort, always. Sometimes.

Anyway, finding out they got into the same university just got ten times more interesting. 

Notice the sarcasm. 

.

.

.

The summer before college is mostly uneventful. 

If you consider Casey dying his fucking hair black uneventful.

She’s definitely more devious than Derek’s been giving her credit for. Because _his hair_. 

Sure, she had done it in retaliation for when he had donated all her wardrobe to charity without her consent, but _his hair_.

His precious hair.

One could only be so cruel. 

Then again, it kind of backfired on her because he still looks damn good with it. 

But _his hair_. 

They don’t speak for a week. 

Aside from that, it’s all pretty tame until they go over to Felicia’s lodge.

They spend a week there, Derek flashes his heart of gold, they make a good deed, and he has to admit it feels pretty damn good.

If anyone asks, he did it for the praise. 

On one of their last days there, he crosses the lake to go see Roxy, his hot, less-bitchy-than-she-appears, summer fling. 

When he gets there, she’s frantically going around the place, packing a pink suitcase.

“Hey,” he says, stepping over some girly stuff scattered across the floor. “You’re… leaving?”

Roxy looks up at him briefly, “My mark cleared.”

Derek pauses.

“…What?”

He suddenly realizes that she’s crying, but she doesn’t look sad, she looks… _euphoric_. 

“I knew it was her,” she says with a watery laughs as she rolls the wire around her curling iron. “We’ve known each other forever and I always knew it was her.”

Derek doesn’t really know what to say, so he just shifts on his feet, awkward. “Uh, congrats?”

Roxy finally stops what she’s doing and locks eyes with him. The look in her eyes… it makes Derek’s heart twist with _something_ , a desire for a thing that he can’t quite reach. “You know, I’ve been dreaming about her all week,” she sighs. “It feels like destiny.”

She stares off into the distance for a moment, dreamily, and then something seems to snap her out of her reverie, and she looks back at him with wide eyes.

“Oh my god, I’m so sorry,” she says, only half-apologetic. “I mean, this was fun, but…” she trails off awkwardly.

Derek smirks reassuringly at her. “I get it,” he says, but he doesn’t. “Go get her? I guess?”

Roxy laughs and hugs him abruptly, and Derek tenses up, uncomfortable. He really doesn’t do hugs. 

Later, sitting at the dock by himself, he wonders why the hell he feels so bothered. He _really_ didn’t care about Roxy enough for this to bother him. But there was something about that look in her eyes, the pure delight and joy. 

Suddenly, another pair of legs joins his on the water at the edge of the dock. 

“Dinner’s ready,” Casey says. “Weren’t you spending the day with Roxy today?”

Derek leans back on his hands, looking out towards the shimmering light of sunset reflecting on the lake water. 

“She left. Her mark cleared and she went chasing after her true love and all that jazz.”

Casey stares at him with wide eyes. “Oh.”

“You know,” Derek says, quietly. “Sometimes it kind of bothers me.”

She doesn’t need to ask what he’s talking about, she just cocks her head to the side, eying him with a strange look on her face. “Really?”

“I just… I sometimes wonder if this is going to happen every single time. If eventually they are all going to leave me for the same reason.”

The same reason why his mom had left his dad. At least George had the opportunity to go out and get his own soulmate.

When Casey doesn’t say anything, he turns to look at her. She’s staring at him with intense eyes, and his breath kind of catches in his throat. She’s carefully still, her blonde-streaked hair blowing lightly in the breeze, her blue eyes shining.

A beat passes between them, and slowly, her hand lifts towards the zipper of her jumpsuit.

His mouth dries, and his eyes widen fractionally. “What are you doing?”

“Do you trust me?” she whispers.

“What?”

“Do you trust me?”

Her hand is still on the zipper, and without thinking, he nods.

“Don’t freak out,” she says. 

And starts pulling down. 

“DINNER’S READY!” 

They both jump at Marti’s voice, and suddenly the girl appears from behind the bushes, throwing herself on Derek’s back. “Piggy back ride, Smerek!”

Casey pulls her legs out of the water and bolts out of sight, and Derek needs another moment to compose himself before he grabs Marti and starts tickling her. 

Later, she doesn’t offer to show him again, and he doesn’t ask. 

.

.

.

Casey goes to New York. Derek goes to Queen’s.

So much for experiencing college together.

Even if he’s a little bitter _(he’ll deny it to his dying breath)_ he has to admit, that if someone had come to scout him for hockey, he wouldn’t have hesitated.

So, Derek takes advantage of her absence, and lives the full college experience. 

That is, endless parties, getting black-out drunk every weekend with his new friends from the hockey team, and a different girl in his bed every Friday.

He doesn’t think about the fact that he always picks them brunette and blue eyed. Hadn’t he always had a thing for blondes?

He tries to ignore it, tries to convince himself that he doesn’t miss her. 

Why the hell would he miss her? This is the life he’d dreamed about ever since she moved into his house!

But even if he tries to avoid it, that afternoon at the dock is all he can think about when he tries to go to sleep. 

_Do you trust me?_

He pulls the pillow over his head to muffle her voice.

_Don’t freak out._

.

.

.

It starts on his second month at Queens, when he’s sitting on a bench in between classes and he feels something on his shoe.

He looks down to find a Schnoodle sniffing him, and he has a soft spot for that particular breed, so he absently reaches down to ruffle his ears while its owner looks at him apologetically. When the dog stands on its hind legs and puts his front paws on Derek’s knees, he catches a glimpse of his name tag.

And promptly bursts out laughing.

“Can I please take a picture of Bob?” he asks the owner. “My… my friend would really like it.”

He takes a picture of the dog where you can clearly see his tag and immediately sends it to Casey, accompanied by the caption: **‘He’s alive!!! :D’**

Five minutes later, his phone is ringing with Casey’s caller ID flashing on his screen, and the excitement almost knocks him flat on the bench. 

And so they start texting. And calling.

A lot.

On one occasion they even talk through the night, and he almost jumps out of his skin when his alarm goes off and he suddenly realizes it’s morning and he has to go to class.

And just like that, missing her becomes easier.

And harder. 

He feels weird every time she mentions Jesse, and he’s not stupid enough to keep denying to himself what’s happening to him.

This is not just some teenage hormone-induced attraction anymore. She’s no longer just his hot step-sister, who he sometimes has heated moments with that he’d never _(actually)_ consider taking to another level.

And it’s really fucking stupid on his part, to feel this way. He knows that. 

She’s still his step-sister.

And she still has a soulmate, one that someday she’s going to meet and even if she felt something for him back, she’d never _ever_ pick him over them.

So he doesn’t delude himself into thinking that he’ll get anything more out of this. 

He still picks up every time she calls. 

.

.

.

His first year is almost over when the whole family takes a trip down to New York to see one of Casey’s shows. 

He’s excited to an embarrassing point, but he still manages to complain almost the entire time, only shutting up when Casey’s on stage, and _damn_ , she was always a pretty incredible dancer, but somehow she got better.

They wait for her in the theater’s hall. She comes out of the changing rooms with her hair curled and glittery stage make-up still on her face. Derek’s breathing becomes erratic at the sight of her, and it takes him three whole seconds to notice that Jesse is with her, their hands clasped as they make their way towards the family.

Casey detaches her hand from Jesse’s to hug everyone, pausing as she stands in front of him.

“Hey,” she breathes. He’s not breathing at all.

And then she throws herself in his arms, not giving him room to avoid it. Not that he wants to. 

“Hey, Spacey,” he whispers into her hair. She tightens her arms around his neck once before she lets go, moving aside to reveal Jesse behind her.

“Hey, man. Nice to see you again.”

Derek eyes the other boy carefully, there’s something about the way he’s looking at him that makes him uneasy, although it’s not a hostile look. Finally, he stretches his hand out for Casey’s boyfriend to shake.

After that, Jesse leaves and the family goes out for pizza. Casey sits next to him immediately, and talks relentlessly the entire dinner. 

As they are standing up to leave the restaurant, she turns to him, an awkward look on her face. It’s weird, they’ve been texting and calling constantly for the past few months, but seeing each other in person, with their family around, somehow everything feels different. 

“Jesse and I are going to a party with the cast,” she says, hurriedly. “Wanna come?”

A party with Casey and her boyfriend _(and theater geeks)_ sounds like the least attractive way to spend his night that Derek can think of, but there’s something in the hopeful glimmer of her eyes that makes him say yes.

The three of them end up in a rooftop party, the entire area decorated with fairy lights and full of laughing and dancing people. 

It’s actually pretty decent, and who would have thought this kind of people knew how to throw a party? Maybe it’s true what they say in college, that everyone knows how to have a good time in the right environment. 

He’s leaning against a brick wall nursing a beer. Jesse is beside him, and they’ve fallen into a companionable silence as they watch Casey talking to a group of people a few paces away from them. 

A girl offers Casey her drink and she eyes it suspiciously for a second before taking a hesitant sip, and promptly falling into a coughing fit. The rest of the group – her friends – all laugh, but it’s not at her, it’s with her, and Casey straightens and joins in on the laughter, looking back towards Derek and Jesse with a big smile and giving them a thumbs up.

They both smile and lift their drinks towards her, and she turns back to her conversation. Derek suddenly realizes that she _fits_ here. She’s comfortable, and happy, and successful, and people love her.

He swallows hard a gulp of beer as a thought assaults his mind. 

_She’s never leaving this place._

“Are you okay?” Jesse asks him suddenly.

Derek wrenches his eyes away from Casey and shrugs. “I’m just surprised at how well adjusted Space Case is here. I mean, you should have seen her in high school.”

Jesse hums, lifting one shoulder. “Everyone comes into their own when they’re in a big city. It’s kind of a requirement, to be yourself and find your people. The pace kills you otherwise.”

Derek turns towards her again. “Seems like she finally found her place.”

There’s a few beats of silence before Casey’s boyfriend looks at him seriously. “She’s going back to Canada for school next year.”

“I don’t know if that’s a sure thing,” Derek says. 

Jesse snorts and shakes his head, looking towards Casey with a cryptic smile that Derek doesn’t understand. “Yeah, it is.”

The reassurance sends a pathetic thrill through Derek’s nervous system, and he clears his throat awkwardly, rubbing the back of his neck to hide his smile.

“Why are you guys together if you know it’s doomed?” He asks after a while. He’s never been one to sugar coat things, and Jesse doesn’t seem to mind his lack of tactfulness. 

The other boy shrugs easily. “Because we made things clear from the start.” 

And Jesse’s right, because when summer rolls around, Casey comes back. 

Derek offers to pick her up at the airport. He’s holding a glittery pink sing with the word ‘Princess’ written on it, and waits until she appears through the multitude. 

She sees him, and her walking stutters. She looks confused for a second before her smile lights up her whole face and his stomach _lurches_. 

And _damn_. 

He has no idea how he’s going to survive the next three years at Queens. 

.

.

.

They’ve always walked a very thin, very dangerous line, but did he seriously have to go and fall in love with her? 

It’s not like he’d actively been avoiding it, but he’d known when she came to Queens that he was already at the edge of the cliff, so why the hell had he jumped right in and started hanging out with her religiously instead of keeping his distance?

He watches her cry over Jesse. He takes her to her first real college party. He lets her reel him into study sessions. He watches her date other people. He introduces her to everyone he knows. He lets her say out loud, to people, that they are _friends_.

And all the while he falls, without a safety net, harder and faster as time passes, and really, he only has himself to blame.

He can’t bring himself to regret it when she looks up from her textbook and smiles.

.

.

.

“Ugh,” Casey mutters from beside him. “Lana at 12 o’clock.”

He follows her gaze towards the other end of the cafeteria, where a short, brunette girl is standing, glaring at them.

“Want me to go beat her up?” he says, half-joking.

“God, no,” Casey snorts. “Let’s just leave.”

He looks up again and locks eyes with the girl, who mouths ‘Fuck you, Venturi’ towards him. She’s the captain of the girl volleyball team, owns more leather jackets than anyone he knows, and dated Casey for a month before their relationship ended, in Casey’s words ‘catastrophically’. 

She also hates Derek with a burning passion, and he doesn’t want to admit that the feeling is mutual, but when Casey’s not looking, he scratches his nose with his middle finger and stirs Casey along towards the cafeteria doors with a hand on the small of her back, smirking as Lana bristles.

“You never did tell me what happened with her,” he says when they are out in the quad.

Casey shakes her head. “She was mad that I never showed her my mark, but I think it’s more about the fact that I wouldn’t let her take off my shirt.”

“Asshole,” Derek mutters, and she nods in agreement. “You _are_ weird about the mark thing,” he says a few seconds later.

She shrugs. “It’s a private matter.”

“Come on, no one’s ever seen it?” Derek asks. “Not even Emily?”

Casey gets a weird look on her face. “Well… Jesse has.”

Derek stops in his tracks. “What? You just decided to show him?”

“Well…” she trails off, and suddenly it hits him. Casey and Jesse dated for a year, away from Canada, and maybe it’s not so much that she just showed him but more that he _got_ to see it. He feels nauseous. 

He swallows hard the realization, and tries to keep a joking tone. “So you don’t trust me? I swear I wouldn’t tell anyone.”

Casey snorts. “Is that a serious question?”

“Casey.”

“Of course I trust you Derek,” she says, in an exasperated tone of voice. “But my mark, that’s… it’s different.”

“Yeah, but you trusted Jesse.” He knows he’s being jealous and downright ridiculous, but he can’t help but feel a little betrayed. Jesse is not even in her life anymore.

“Well, I’m not having sex with you!” Casey snaps.

It takes a few seconds before he can answer, and her face looks pained. He doesn’t know if it’s embarrassment or something else.

“Well, _obviously_ ,” he says, finally. “Look, I have to get to class.”

They don’t see each other for three days after that.

He knows he was being stupid about the subject, so he extends the olive branch, appearing at her dorm with take out from her favorite veggie place.

They don’t talk about it again. 

.

.

.

He remembers all those times coming home drunk from parties while they were still in high school, and her disapproving glare the mornings after while he did his best to try and hide his hangover from his dad and Nora. 

He can’t believe that now she’s getting drunk _with him_.

They are a week away from finals, and somehow, Derek convinced Casey to come to a party in an apartment outside campus with him. They don’t even know the name of the host, a piece of information that had Casey yelling at him like he was trying to get them murdered, but that now she finds hilarious, as she finishes her third beer.

“All right, I’m cutting you off,” he says, as he takes the bottle away from her and downs the last few gulps of the lukewarm liquid, grimacing. “Ugh, this is disgusting, Case.”

He walks a few paces away from her and settles the bottle on a nearby table. When he turns around, there’s a tall, dapper guy talking to her, and Derek leans back against the table, irritated. To his surprise, the guy simply walks away and Casey looks around, as if wondering where Derek had gone.

Derek goes back to her side, and she smiles at him. “Hey, there you are!”

“Normally, that’s the kind of guy you’d go for,” he tells her, nodding in the direction the other boy had disappeared.

Casey shrugs, giving him a weird look. “Nah, I‘m just waiting for my guy now.”

He tries to hide the feeling of his heart falling with a raised eyebrow. “You are?”

“Yeah, I am.” 

Is he imagining the way she’s looking at him? For a while now he’s been feeling like her looks mean more than what she’s letting on, yet here she is, telling him she’s giving up on dating and ready to wait for her soulmate to come around. 

Wait.

“So it _is_ a guy.”

Instead of spluttering at her slip-up, Casey just shrugs nonchalantly. A group of girls forms right beside them, squealing and pushing them to the side, so they start moving away to a less crowded area of the apartment.

Derek laughs. “I must say, I’m kind of relieved. With all the secrecy I was kind of scared that it was like, one of my ex-girlfriends or something.”

Casey trips and his arm shoots out to steady her. He mutters a fond ‘Klutzilla’ under his breath, and when the hell had that become a term of _endearment_? 

She blushes to the roots of her hair, and he watches, fascinated. “De-rek!”

Lapping it up, he lightly elbows her side. “Oh, come on. I always thought there was something going on between you and Sally.”

Her jaw drops, indignant. “She was my friend!”

Loving seeing her so flustered, he presses. “Are you saying you didn’t find her the least bit attractive?”

Casey looks away from him, a strange look on her face. “I mean, don’t get me wrong, Sally was cute. But, you… loved her.” Her voice waivers. 

He coughs, feeling the moment grow awkward, which was totally not the goal. “I was just kidding, Case.”

At that, she turns to look at him, a suddenly mischievous sort of glint in her eye. “Now, Kendra, on the other hand…”

Derek chokes. “ _What_?”

She shrugs, defensively, face still red as a brick. “What? She was hot.”

“You and _Kendra_?”

Her eyes bulge comically. “No! Nothing ever happened. It was just a tiny crush”

Derek doubles over, laughing. “You two had like, _nothing_ in common.”

Casey hits him on the shoulder. “It was just something about her attitude.”

“What, the arrogance?”

She claps sarcastically. “Wow, that’s a big word, D! Congrats.” 

Derek can’t help but find it infinitely adorable that she can still banter so well while being so embarrassed. And god, he’s like, so totally beyond gone for her, it’s not even funny anymore. It’s been too long for it to be funny.

And when Casey doesn’t deny what he said, he realizes something. “You have a _type_ ,” he says, raising his eyebrows. He remembers Truman, and Max, and even Lana. He’d always thought that Casey liked assholes, but now that he thinks about it, maybe ‘arrogant’ is a better word to describe it. 

She looks at him again, that weird spark returning to her eyes tenfold, and his stomach turns. She looks him up and down, shamelessly. “I _do_.”

And this cannot be just wishful thinking. He can’t be imagining the way she’s looking at him.

Casey McDonald is _flirting_ with him. Openly, and unabashedly, and god, he doesn’t want to admit it to himself, but this is kind of like a dream come true. 

“Oh?” he says, the word coming out a little strangled.

She opens her mouth, whatever she’s about to say completely muffled by the shouts of the hockey team, who just spotted them and are coming their way.

And yeah, he’s gonna kick some asses at practice on Monday.

.

.

.

He can’t pinpoint the moment. He doesn’t know when exactly everything shifts, but their entire dynamic keeps changing day by day.

Time moves forward, and Casey’s smiles become more dazzling than ever. Her eyes and her touches linger, her words become suggestive, and he knows he’s not crazy, but he’s still scared shitless. 

What is she doing, playing with fire like this? How is she not running away from this between them? 

He’s always been the reckless one, but somehow, it’s him that evades every opening she gives him, ultimately stopping himself because of one thing, and one thing only.

That name imprinted on the left side of her ribs.

Because hell, he’s in love with her – crazily and pathetically so – but that doesn’t mean he’s willing to risk getting his heart destroyed.

Not when the possibility of her leaving him for the real deal is so painfully obvious.

.

.

.

“You used to be better at this,” Marti says, taking a seat beside him. “Are you even _trying_ to hide it?”

Derek takes his eyes away from Casey’s retreating back as she exits the house with Lizzie. 

“Excuse me?”

Marti raises her eyebrows, sending him a look. “Do you _want_ me to spell it out for you?”

Derek huffs, throwing his head back against the couch cushions. “No, thanks.”

“You still haven’t told her?”

He cringes. Somehow, he had been hoping that his sister wasn’t talking about what he thought she was talking about, but of course she is. “It’s complicated,” he says.

Marti throws her legs over Derek’s lap. “Girl likes boy, boy likes girl, how complicated can it be?”

He snorts. “ _Much_ more complicated than that.”

“You know she loves you back, right?” she asks, matter of fact. Derek chokes on air for a moment, before looking at her with wide eyes. Marti rolls her eyes and slugs him on the shoulder. “I’m serious!”

“Look Smarts,” he says, putting a hand on her knee for her to be quiet. Nora’s in the kitchen with his dad getting dinner sorted. “I _know_ she feels something, okay? That doesn’t mean it matters.”

Marti looks at him like he’s insane. “Why the fuck wouldn’t it matter?” 

Derek winces and pinches her leg in chastening, making her hit him again. Marti swears too much for a 12 year old. He has no idea where she got it from. 

“Language,” he says. “Having feelings is not enough to make her choose her stepbrother over her soulmate.”

Marti pauses, and stares at him with an unreadable expression on her face for a while.

“Oh, Smerek,” she says pityingly, after a while. 

“What?” he huffs, annoyed.

Marti pats his head condescendingly. “You’re so damn _stupid_.”

“ _What_?”

She shakes her head and moves to get up from the couch.

“Hey!” he calls after her.

“Just tell her, Smerek,” she says softly.

.

.

.

Eventually, he cracks. 

They are studying at her dorm. Her roommates are out, and her pen keeps shifting from tapping softly against her knee, to her chin, to her mouth while she occasionally hums softly to herself in utter concentration – and he can’t take it anymore.

“Okay, I can’t do this anymore.”

Casey doesn’t even look up from her notes. “What, studying? I’m afraid you still have another year of this, D.”

“Not studying,” Derek says, frustrated. She looks up and his heart starts pounding. He considers backing down, but there’s something in her eyes that makes him spit it out. “ _This_ , us.” 

She swallows. “Us?”

Derek rubs his face tiredly. “Yeah, don’t play dumb with me Space Case. You know what I’m talking about.”

“Okay,” he hears her say. “I thought there would be less talking involved.”

Derek drops his hands from his face. “What?”

The smallest ghost of a smile is on her face, and she meets his eyes intensely.

“When you came around. I thought there would be more… action.”

He chokes a little, “When I came around?”

“Well, yeah.” She blushes a little, a trembling hand coming up to tuck a lock of hair behind her ear. “I mean, I’ve been kind of obvious.”

Despite his strong suspicion that this between them wasn’t something that was just happening inside his head, the admittance that she had, in fact, been acting on her feelings for him knocks the air right out of him. 

“I couldn’t just, come on to you out of nowhere,” Derek says, shocked.

Casey snorts. “It wouldn’t have been out of _nowhere_.”

Well, understatement of the century, but that’s not the point. 

“That’s not what I meant. Don’t you think we should have a conversation about how we’re gonna do this?”

Casey has the decency to blush to the roots of her hair. “Do what?”

Derek stands up from her bed, throwing his arms out in frustration and starting to pace. “Whatever the hell this is! God, one would think _you’d_ be the one dying to set all the terms.”

“What terms, Derek?”

Is she playing dumb on purpose? 

“Like, what do you want out of this? What should I expect? What’s gonna happen when ‘your guy’ comes along?”

“… My guy?”

Derek stops pacing and turns to face her, meeting her eyes and ignoring the pathetic way in which his stomach rolls over. “Your _guy_ , Casey.”

At last, realization dawns on her face. “Oh.”

“Yeah, oh.” He lets himself slump on her desk chair. “I can’t believe you didn’t think about this.”

There’s a few moments of silence in which he looks at her ceiling, because if he looks at her for more than 5 seconds, he’s afraid he might just jump her and avoid the conversation altogether. He can’t jump into anything with her without knowing exactly what he’s getting into. This could kill him. 

“You think I didn’t think about this?” Casey’s voice is low and steady, the kind of tone that carries the calm before the storm. He snaps his eyes back to hers, and sure enough, they look dark and thunderous. “You think I haven’t been thinking about this for years?”

“ _Years_?”

“Yes, Derek. _Years_.”

Derek shakes his head, confused. “What do you – What are you talking about?”

They hold each other’s gaze for a long moment, and then Casey takes in a shaky breath. “You know what? I’ll just – “

Her hands go to the hem of her shirt and her eyes lock with his, something alive sparkling in the blue. Suddenly he’s transported to that sunset, sitting at the dock in her grandmother’s lodge, the look she had given him in that moment before her hand went to the zipper of her jumpsuit. It was that same look of hope, begging for his understanding.

_Do you trust me?_

Heart hammering inside his chest, he gives her a little nod and holds his breath.

_Don’t freak out._

Casey lifts up her shirt.

Derek watches the smooth, pale skin of her stomach as it appears, as the fabric goes up and up, painstakingly slow until it’s reached the underside of her bra, and then Casey shifts, showing him the left side of her torso, and his eyes fly to the black inscription on her ribs.

And he stares.

**Derek Venturi**

Casey waits until he finally takes his eyes off the mark, her mark, her _soulmate mark_ that has _his name_ on it, and meets her eyes again. There’s a soft look on her face, and her voice trembles when she says. “So, how do you want to do this, Derek?”

It takes another moment until he can use his voice, and he shakes his head. “I don’t understand. How long? All this time…”

She nods. “Yeah, since the beginning. Believe me, I prayed for it to change but…” She grimaces, as if she’s embarrassed of what she’s about to say. “It’s always been you.”

And as much as her words send his heart into a flat line, there’s a ringing in his ears, and he reacts the only way her knows how to.

He’s angry. 

He jumps from the chair. “Why the hell didn’t you tell me?”

And Casey reacts the only way _she_ knows how to. She’s defensive. “When was I supposed to tell you? When we were sixteen?” She laughs derisively. “I don’t know if you remember the part where we were step-siblings, and you were an asshole.”

“I wouldn’t have been an asshole about this!” he shouts.

Casey stands up too. “How could I have known?”

“You would have if you had told me!”

She throws her hands in the air. “Well, I can’t go back in time and change it now, Derek.”

Derek shakes his head and starts pacing again. “We are soulmates. We are _soulmates_.” He has a soulmate. _Casey_ is his soulmate. He’s not alone, he has _her_. They are soulmates. For a moment he feels the elation, but then he remembers that she’s known this for four years. “You had two years of college to tell me!”

Casey sighs, and runs a hand through her hair. “Yes, Derek. We are soulmates. Are you going to stay mad at me about this forever?”

He looks away from her. “I’m assimilating it!”

“Fine, take all the time you need.” She starts grabbing her stuff to leave... which is ridiculous, because she lives here, but she’s dramatic like that, and fuck it if it’s not still endearing to him. 

Derek groans. “Stop, Casey. Stop!”

They stare at each other, and his resolve crumbles.

“Fuck, Casey, I love you. Do you know how long I’ve been hiding that, afraid that it could never happen between us when you had my name, _my name_ on your skin the entire time?”

Casey looks down, ashamed. “Well, I was scared.”

Derek runs a hand down his face, frustrated, and looks up at her to find her smiling at him.

“What?” he snaps.

“You just said you love me.”

He feels like raising his shoulders in defiance like a little kid. “Yeah, so?”

Casey smiles brighter. “I love you too, you know?” His shoulders slump, and he feels his heart expanding and his anger start to slip away from him. “I think I would have fallen in love with you regardless.”

She starts moving towards him and his heartbeat goes crazy. Derek tries his best to grasp at any remnant of his anger. “I’m mad at you,” he warns her.

She just smirks and keeps walking towards him. “I’m sorry.”

“Do not come any closer,” he says, but his voice trembles, and he can see in her face that she knows she’s winning, and fuck, hadn’t he once vowed to never let her win? 

“We’ll fight about it later, I promise,” she says.

She doesn’t finish crossing the distance towards him before he’s kissing her.

.

.

.

Derek wasn’t born with a soulmate mark. Be it destiny, or fate wanting to make things harder, or simply a biological mistake, he just doesn’t have a mark. And that’s fine, he doesn’t need one. 

He has a soulmate all right.

_The end._

**Author's Note:**

> Hope you liked it :)
> 
> The second part of this series is a very little something from Casey’s POV, because like halfway through outlining this I realized that her POV of this whole situation must be an angst fest and I love making them suffer <3
> 
> So, I’ll post that soon.
> 
> -Mey


End file.
